This invention relates to a testing machine adapted to perform an endurance test and the like of bearings to be rotated around a main shaft and rotated around their own axes, such as a needle cage applied between the large end of a connecting rod and a crank pin of an internal combustion engine to be remarkably effected by centrifugal force.
There has been known as a testing machine for conducting a life test or the like of bearings a testing machine for loading a static load or a variable load as described on pages 31 to 39 of an organ "Lubrication" Vol. 7, No. 1 issued by the Japan Lubrication Society (on Jan. 1, 1962).
As schematically shown in FIG. 3, in this conventional testing machine, bearings B to be tested are mounted at both ends of a main rotational shaft A to rotate the bearings B to be rotated integrally with the main rotational shaft A, and loads are applied to the bearings B to be tested through a load frame E by a spring D for applying a load to the bearings B to be tested in a direction of an arrow C. The bearings B to be tested are tested by maintaining the load by the spring D constant or varying the load in a sine curve state.
As apparent from FIG. 3, in the conventional testing machine, the rotational frequency of the bearing B to be tested is always the same as that of the main rotational shaft A, and this testing machine cannot perform an endurance test of bearings in a state that centrifugal force is applied to the bearings, i.e., in a state that the bearings B to be tested are rotated around the main rotational shaft A and also around their own axes simultaneously.